Iron sulfide dissolver

Abstract

An aqueous iron sulfide dissolver including zinc, chromium, a methoxybenzoic acid, formic acid, acetic acid, and hydrochloric acid. The iron sulfide dissolver is made by combining these components, and dissolves compounds including iron sulfide upon contact. Evolved hydrogen sulfide reacts with the methoxybenzoic acid to yield solubilized methanethiol as an intermediate product, which is further oxidized to yield dissolved dimethyl disulfide.

What is claimed is: 
     
       1. An aqueous iron sulfide dissolver comprising:
 zinc; 
 chromium; 
 a methoxybenzoic acid, wherein “methoxybenzoic acid” refers to the methoxybenzoic acid and its conjugate base; 
 formic acid, wherein “formic acid” refers to formic acid and its conjugate base; 
 acetic acid, wherein “acetic acid” refers to acetic acid and its conjugate base; and 
 hydrochloric acid, wherein “hydrochloric acid” refers to hydrochloric acid and its conjugate base. 
 
     
     
       2. The aqueous iron sulfide dissolver of  claim 1 , wherein the methoxybenzoic acid comprises a trimethoxybenzoic acid. 
     
     
       3. The aqueous iron sulfide dissolver of  claim 2 , wherein the trimethoxybenzoic acid comprises 3,4,5-trimethoxybenzoic acid. 
     
     
       4. The aqueous iron sulfide dissolver of  claim 1 , wherein the methoxybenzoic acid comprises a dimethoxybenzoic acid. 
     
     
       5. The aqueous iron sulfide dissolver of  claim 4 , wherein the dimethoxybenzoic acid comprises syringic acid (3,5-dimethoxy-4-hydroxybenzoic acid). 
     
     
       6. The aqueous iron sulfide dissolver of  claim 1 , wherein a molar ratio of the zinc to the chromium is in a range of 1 to 3. 
     
     
       7. The aqueous iron sulfide dissolver of  claim 1 , wherein the molar ratio of the zinc to the chromium is in a range of 1.5 to 2.5. 
     
     
       8. The aqueous iron sulfide dissolver of  claim 1 , wherein a molar ratio of the formic acid to the chromium is in a range of 3.5 to 5.5. 
     
     
       9. The aqueous iron sulfide dissolver of  claim 1 , wherein a molar ratio of the acetic acid to the chromium is in a range of 2.5 to 4.5. 
     
     
       10. The aqueous iron sulfide dissolver of  claim 1 , wherein a molar ratio of the hydrochloric acid to the chromium is in a range of 1 to 3. 
     
     
       11. The aqueous iron sulfide dissolver of  claim 10 , wherein the molar ratio of the hydrochloric acid to the chromium is in a range of 1.5 to 2.5. 
     
     
       12. The aqueous iron sulfide dissolver of  claim 11 , wherein the molar ratio of the hydrochloric acid to the chromium is in a range of 2 to 2.5. 
     
     
       13. The aqueous iron sulfide dissolver of  claim 1 , wherein a molar ratio of the methoxybenzoic acid to the chromium is in a range of 1.1 to 2.5. 
     
     
       14. The aqueous iron sulfide dissolver of  claim 13 , wherein the molar ratio of the methoxybenzoic acid to the chromium is in a range of 1.5 to 2. 
     
     
       15. A method of making an aqueous iron sulfide dissolver for dissolving iron sulfides, the method comprising:
 combining zinc, chromium, a methoxybenzoic acid, formic acid, acetic acid, and hydrochloric acid to yield the aqueous iron sulfide dissolver. 
 
     
     
       16. The method of  claim 15 , wherein the zinc is in the form of zinc metal. 
     
     
       17. The method of  claim 15 , wherein the chromium is in the form of a chromium salt. 
     
     
       18. A method of dissolving an iron sulfide, the method comprising:
 contacting an iron sulfide with an aqueous iron sulfide dissolver comprising zinc, chromium, a methoxybenzoic acid, formic acid, acetic acid, and hydrochloric acid to dissolve the iron sulfide; 
 reacting evolved hydrogen sulfide with the methoxybenzoic acid to yield methanethiol; and 
 dimerizing the methanethiol to yield dimethyl disulfide in solution. 
 
     
     
       19. The method of  claim 18 , further comprising introducing the aqueous iron sulfide dissolver into a wellbore, wherein contacting the iron sulfide with the aqueous iron sulfide dissolver occurs downhole. 
     
     
       20. The method of  claim 18 , further comprising removing the dimethyl disulfide from the solution.